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Part A helps cover inpatient hospital care, skilled nursing facility care in qualifying circumstances, hospice, and some home health care. Part B helps cover doctor visits, outpatient care, preventive services, and durable medical equipment.

Part C, also called Medicare Advantage, is an alternative way to receive your Medicare Part A and Part B benefits through a Medicare-approved private plan. Many plans include Part D prescription drug coverage. Part D helps cover prescription medications.

Medicare Supplement Insurance, also called Medigap, is different from Medicare Advantage. It works with Original Medicare to help pay certain out-of-pocket costs.

For most people, the Initial Enrollment Period is a 7-month window: it starts 3 months before the month you turn 65, includes your birthday month, and ends 3 months after that month.

If you have health coverage through your or your spouse’s current employment, different rules may apply. Before delaying Part B, confirm whether your coverage is based on current employment and whether it qualifies for a Part B Special Enrollment Period. Retiree coverage and COBRA generally do not provide the same Part B enrollment protection as active-employment coverage.

Original Medicare is Part A and Part B administered by the federal government. You can generally see any provider nationwide who accepts Medicare, and you can add a stand-alone Part D plan and may choose a Medigap policy.

Medicare Advantage is offered by private insurance companies approved by Medicare. Plans must cover Part A and Part B services, but may use provider networks, referrals, and plan-specific cost-sharing. Many also include prescription drug coverage and additional benefits. Compare the details of each plan before choosing.

If you have Original Medicare, you can generally get drug coverage through a stand-alone Part D plan. Many Medicare Advantage plans include prescription drug coverage, while some do not.

If you delay Part D and go 63 or more consecutive days without creditable prescription drug coverage after your initial enrollment opportunity, you may have to pay a late enrollment penalty if you enroll later. “Creditable” means the other coverage is expected to pay, on average, at least as much as standard Medicare drug coverage. Check with your current benefits provider if you are unsure.

Sometimes. Which coverage pays first depends on factors such as whether the coverage is based on current employment, the size of the employer, and your situation. Retiree coverage and COBRA have different rules from active-employer coverage. Talk with your benefits administrator and Medicare before making decisions about delaying or dropping coverage.

The Medicare Annual Enrollment Period runs from October 15 through December 7 each year. During this time, people with Medicare can make certain changes, such as joining, switching, or dropping a Medicare Advantage plan or Part D prescription drug plan, or moving between Original Medicare and Medicare Advantage. Changes generally take effect January 1.

The Medicare Advantage Open Enrollment Period runs January 1 through March 31. It is for people who are already enrolled in a Medicare Advantage plan on January 1. During this period, you can switch to another Medicare Advantage plan (with or without drug coverage), or return to Original Medicare and join a stand-alone Part D plan.

This period is not a general opportunity for someone with Original Medicare to switch between stand-alone Part D plans.

A Special Enrollment Period is a limited opportunity to make certain Medicare coverage changes outside the usual enrollment periods when a qualifying event or circumstance occurs. Examples may include moving, losing certain health or drug coverage, changes in Medicaid or Extra Help eligibility, or living in or moving out of an eligible institution.

The changes you can make and the time you have depend on the specific SEP. Not every life change qualifies, and some SEPs apply to Medicare Advantage or Part D plans while others apply to enrolling in Part A or Part B.

It may. If you move outside your current Medicare Advantage or Part D plan’s service area, or move somewhere with new plan options, you may qualify for an SEP. The timing generally depends on when you move and whether you notify your plan before the move.

Contact your plan or Medicare promptly after a move so you can confirm your specific deadline and choices.

Possibly. Losing Medicaid can create an SEP with a specific time window to make certain Medicare Advantage or Part D changes. People who have Medicaid or receive Extra Help may also have additional opportunities to change certain drug coverage or plan options. The available changes and timing depend on the type of assistance and the circumstances.

If you receive a notice about a change in Medicaid or Extra Help, keep it. The notice date and effective date may help determine which enrollment rules apply.

Losing certain employer or union health coverage, including some drug coverage, may qualify you for an SEP. The length and start of the enrollment window depend on the type of coverage lost. Before coverage ends, ask the benefits administrator for the exact end date and whether the prescription coverage is creditable.

Not automatically. Some people with qualifying chronic conditions may be eligible to enroll in a Chronic Condition Special Needs Plan (C-SNP), if one is available and they meet the plan’s eligibility requirements. Certain SEP rules may apply, but having a diagnosis by itself does not mean every Medicare plan can be changed at any time. Eligibility and timing should be confirmed before submitting an enrollment.

Most people do not pay a premium for Part A if they or a spouse paid Medicare taxes long enough while working. Most people pay a monthly Part B premium. The amount can change each year and may be higher for people with higher incomes. Medicare Advantage, Part D, and Medigap premiums vary by plan and location. You may also have deductibles, copayments, and coinsurance.

For current costs, visit Medicare.gov’s Medicare costs page.

You may have to wait for another enrollment period and could face a gap in coverage or a late enrollment penalty. There are exceptions, including certain Special Enrollment Periods when you have qualifying coverage through current employment. The rules are different for Part A, Part B, and Part D, so check your situation before delaying enrollment.

It depends on the plan. Medicare Advantage plans may have provider networks, and network participation can vary by plan and year. Before enrolling, check each doctor, hospital, and specialist directly with the plan and provider. Also review referral requirements and out-of-network costs. With Original Medicare, you can generally see providers who accept Medicare.

Not necessarily. You can generally apply for a Medigap policy at any time, but outside certain guaranteed-issue rights or protections, an insurance company may be able to use medical underwriting and could deny the application or charge more, depending on state law. If you are considering leaving Medicare Advantage, check your Medigap eligibility and acceptance before making a change. State-specific protections may apply.